CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of U.S. Provisional Application No.62/949, 866, entitled “Strainer Mixer Architecture Assembly” filed Dec. 18, 2019. This application is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. This is particularly true in the case of offshore operations where expenses may grow exponentially long after the completion of the well. For example, subsequent routing intervention and maintenance may require considerable more time, effort and cost at the subsea oilfield. [0003] In recognition of these potentially enormous expenses, added emphasis has been placed on well monitoring and maintenance throughout the life of an oilfield. Maintaining production from a host of wells at an oilfield often requires the use of pumping to aid in recovery of production fluids, whether through the use of single or multiphase pumps, gas compressors or other pumping equipment. This may be particularly true in the case of offshore oilfields. Along these lines, a host of pumps are generally incorporated into the layout of the field along with a variety of other production flow enhancing equipment.

[0004] Pumps may be used to enhance production by reducing wellhead pressure to allow a more rapid depletion and to lift weak wells in concert with production flow from stronger wells. Multiphase pumps are also used in the field layout due to the often inconsistent or changing nature of the production fluids. That is, produced fluids may be a mixture of liquid and gas for which multiphase pumps are particularly adept at managing in terms of maintaining a continuous flow.

[0005] Of course, other issues may be present in the flow. For example, not only is the production fluid sometimes prone changing liquid and gas percentages, but production fluid often presents with a fair amount of debris. This may present particularly challenging issues where the oilfield layout relies on a distribution of pumps to promote production flow as described above. This is because produced debris is prone to being wedged or caught within pump impellers or other moving pump components, particularly as higher flow velocities are attained. Depending on the size of the debris and pertinent clearance spaces within a given pump, this may lead to a complete loss of the pump and a halt to all operations. Of course, in offshore operations where pumps and multiphase, debris-filled production fluids are likely, such pump losses are more common.

[0006] When the catastrophic event of a pump failure occurs, the event is truly catastrophic in an economic sense as well. Such a failure means that operations at the oilfield will be shut down, perhaps for several months or even a year or more. Over this period a costly, time-consuming intervention must take place to replace the high dollar, blown-out pump with a new one. Subsequently, operations may eventually be restarted. All in all, in today’s dollars, several million dollars worth of intervention time, lost production and new equipment will be lost in order to replace the blown-out pump.

[0007] With such expenses in mind, efforts have been proposed to implement strainers into or nearby oilfield pumps. Thus, debris produced with production fluids may be shielded from reaching and ultimately destroying the oilfield pumps. Unfortunately, the proposed strainers are generally ineffective for a variety of reasons. For example, consider a strainer with a perforated face having pores of a predetermined size through which all pumped production fluids are drawn across in advance of reaching the pump. In theory, this should keep all debris above the predetermined size of concern from reaching the pump and leading to pump damage or failure. As a practical matter, however, other unintended consequences may occur.

[0008] Consider a strainer that effectively filters out such debris as described above. It would not be surprising that over time, the strainer’s perforated face would become clogged with debris. Once more, since all production fluid must traverse this face for sake of filtering, the clogging would lead to a reduction in production flow while harming pump efficiency and even the pump itself. No matter the rate of clogging, given enough time, eventually the production flow would be dramatically reduced, at least in theory. Once more, in actual practice, it is even more likely that the continuously operating pump would place such a strain on the clogged perforated face that the structure of the face would likely deteriorate. That is, the strainer would likely “produce” its clogged perforated face right into the pump thus, assuring its failure.

[0009] The best case scenario is that a conventional strainer might buy some time and delay the ultimate failure of the pump. However, it may be just as likely that the strainer would hasten the failure of the pump. For example, consider a circumstance where debris is strained and filtered out that would not necessarily damage the pump. Nevertheless, the resultant clogging would eventually reduce production flow and likely produce a perforated face to the pump leading to its demise. That is, the effort to safeguard the pump from debris with a conventional strainer may be just as likely to lead to the failure of the pump as taking no such effort at all. Therefore, as a matter of equipment and installation expense alone, operators generally avoid installing such strainers, opting to leave the pumps entirely unprotected from production fluid debris.

SUMMARY

[0010] A method of straining debris from a production fluid. The method includes directing a flow of fluid into a strainer. A perforation mechanism of the strainer may then be used to interface the fluid flow for accumulating debris at a base of the mechanism. Additionally, the fluid flow may be facilitated to an area above the accumulated debris during the accumulation of the debris. Once more, the area above the accumulated debris may include further perforation structure for continued accumulating of debris above the accumulated debris.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a perspective sectional view of an embodiment of strainer for filtering debris from a production fluid flowing at an oilfield.

[0012] Fig. 2A is a side cross-sectional view of the strainer of Fig. 1 illustrating an initial production fluid path therethrough.

[0013] Fig. 2B is a side cross-sectional view of the strainer of Fig. 1 illustrating the production fluid path following an initial degree of debris filtering.

[0014] Fig. 2C is a side cross-sectional view of the strainer of Fig. 1 illustrating the production fluid path following a greater degree of debris filtering than that of Fig. 2B. [0015] Fig. 3A is a perspective view of the strainer of Fig. 1 accommodated by surrounding support structure. [0016] Fig. 3B is a perspective view of the strainer of Fig. 3A where the surrounding support structure includes a modular assembly to accommodate the strainer and a pump. [0017] Fig. 4 is an overview depiction of a subsea oilfield accommodating the modular assembly of Fig. 3B.

[0018] Fig. 5 is a schematic representation of an alternate embodiment of the strainer accommodating a pump therein as a pump integrated mixer (PIM).

[0019] Fig. 6 is a flow-chart summarizing a unique embodiment of employing a strainer with a pump at an oilfield that facilitates production fluid flow.

DETAILED DESCRIPTION

[0020] In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it will be understood by those skilled in the art that the embodiments described may be practiced without these particular details. Further, numerous variations or modifications may be employed which remain contemplated by the embodiments as specifically described.

[0021] Embodiments are described with reference to certain types of subsea oilfield layouts utilizing permanently installed subsea pumps at the seabed to facilitate continuous production from wells of the oilfield. However, no particular layout is required. For example, the system and techniques described herein may be directed at a single well or even utilized in a surface environment. So long as a strainer is associated with a pump that filters out debris while also facilitating production fluid flow, appreciable benefit may be realized.

[0022] Referring specifically now to Fig. 1, a perspective sectional view of an embodiment of strainer 100 is illustrated. The strainer 100 is configured for use in an oilfield environment for filtering debris 200 from a production fluid 185 flowing at an oilfield 401 (see also Figs. 2A-2C and 4). The internal architecture of the strainer 100 is one that presents a variety of differently sized orifices 145, 147, 130, 155. Notably, as the fluid flow 185 enters an inlet 110 of the strainer 100, it may traverse various architectural features, referred to generally here as a “perforation mechanism”, before reaching the outlet 180 and exiting the strainer 100. For example, an unobstructed fluid flow 185 might naturally proceed down the inlet 110 and directly toward a base 155 of an inner housing 160. At this location, base orifices 155 are presented to the fluid flow 185 such that an initial filtering of debris 200 may occur as illustrated in Fig. 2B.

[0023] With added reference to Fig. 2B and as detailed further below, it may be advantageous for the base orifices 155 to be smaller in diameter than other orifices 130, 145 and/or clearances 157, 165 (in terms of clearance width). In this way, the initial filtering of debris 200 by the strainer 100 may be more inclusive, catching the smallest of debris particles filtered out by the strainer 100. However, for reasons also detailed further below, subsequent filtering by other larger sidewall orifices 130 may be sequentially less restrictive. Indeed, at some point, once the inner housing 160 is sufficiently filled with debris 200, the fluid flow 185 may primarily route from the inlet orifices 145 and /or the inlet clearance 157 and through bypass ports 147 at the side of the inner housing 160.

[0024] Continuing with reference to Fig. 1, the structure of the inlet 110 joins the strainer housing 170 at a clamped coupling 125 and extends into the strainer 100, emptying into an inner housing 160. Each of the inlet 110 and the inner housing 160 are equipped with sidewall orifices 145, 130 as suggested above. However, upon initially receiving fluid flow 185 within such a tubular housing, there may be a tendency for the flow 185 to swirl. Therefore, a swirl breaker 175 is installed at the base 150 to prevent the potentially unproductive swirling of debris 200 as well as pothole effects (see Fig. 2). Once traversing the base 150 through the base orifices 155, the fluid flow 185 may empty into the lower space 190 of the strainer 100 and eventually out of the outlet 180 as shown. Of course, there are other pathways for the fluid flow 185 which may arise over time as filtering at the base 150 continues.

[0025] With added reference to Fig. 3B, filtering with the strainer 100 may be of significant benefit for the life of the pump 350 associated with the strainer 100. That is, the pump 350 may be connected to the strainer 100 and other production fluid architecture for sake of maintaining an efficient flow of the production fluid 185. With specific reference to the illustration of Fig. 1, the pump 350 may be fluidly coupled to the outlet 180, making sure to drive up and maintain the efficient flow through the strainer 100. With moving inner parts such as impellers, the pump 350 may be susceptible to the debris 200 shown in Fig. 2B. At the same time, filtering out the debris 200 in a manner that prohibits flow maintenance and clogs the production line is not advantageous and may even be quite harmful to the pump 350. Thus, as described further below, the strainer 100 uniquely filters debris 200 in a sequential manner that allows for continued maintenance of the production flow 185.

[0026] Referring now directly to Fig. 2A, a side cross-sectional view of the strainer 100 of Fig. 1 is shown, illustrating an initial production fluid path therethrough. That is, in advance of any filtered debris 200 as shown in Fig. 2B, the production fluid flow f 85 enters the inlet 110 of the strainer and is directed down through the perforation mechanism architecture. Specifically, the flow 185 exits the inlet 110 directly into the inner housing 160. Without any filtered debris 200 at the base 150 as shown in Fig. 2B, the flow 185 is free to exit through base orifices 155. Thus, no substantial obstruction to the flow 185 is present and the adjacent pump 350 of Fig. 3B may continue to safely operate and enhance the flow 185.

[0027] Referring now to Fig. 2B, a side cross-sectional view of the strainer 100 of Fig. 1 is shown illustrating the production fluid path following an initial degree of filtered debris 200. The illustrated production flow 185, including the debris 200 would initially tend to follow a straight path offered between the inlet 110 and the outlet 180. Even with the interference of the structure of the base 150 present, the swirl breaker 175 may minimize the tendency of the flow 185 to follow a non-linear path. However, once debris 200 from the flow 185 begins to be collected at the base 150, the option of flowing through the base orifices 155 is no longer available. However, as indicated above, the option of rerouting the flow 185 through the strainer 100 is still available. Specifically, notice the flow 185 that is now beginning to move from the inner housing 160 and through sidewall orifices 130. Thus, filtering of the debris 200 takes place in a manner that does not substantially obstruct the flow 185.

[0028] Continuing with reference to Fig. 2B, the base orifices 155 may be smaller for finer initial filtering of debris 200 as noted above. In one embodiment, this may constitute a diameter of between about 2 and 5 mm. In contrast, sidewall orifices 130 may be somewhat larger to increase flow, for example, in the event that the more linear flow through the base 150 has now been precluded. So, for example, in this same embodiment, the sidewall orifices 130 may be between about 5 and 30 mm in diameter. In one embodiment, the sidewall orifices 130 are of a diameter that changes along a gradient, for example, with orifices 130 closer to the base 150 being closer to 5 mm in diameter and those closer to the inlet 110 getting closer to the noted 30 mm in diameter. In this way, as the interior of the inner housing 160 begins to fill with debris 200, an ever-increasing orifice diameter is presented to the flow 185 to help ensure its continuance. On a similar note, with the understanding that the external clearance 165 is not configured for filtering but for providing a flow path to the re-routed flow 185, the width of this clearance 165 should far exceed the base orifice diameter and likely even that of the sidewall orifice diameter.

[0029] Referring now to Fig. 2C, a side cross-sectional view of the strainer 100 of Fig. 1 is shown illustrating the production fluid path following a greater degree of debris filtering than that of Fig. 2B. Specifically, the debris 200 has substantially filled the inner housing 160 over time. Thus, like the base orifices 155, the sidewall orifices 130 have also become occluded. However, another alternate path is provided to facilitate continued flow 185. Specifically, once the sidewall orifices 130 are no longer available, the flow 185 may exit the inlet 110 through bypass ports 147. In contrast to the base 155 and sidewall 130 orifices, the ports 147 are not intended to perform a filtering function. So, for example, these ports 147 may be much larger. In one embodiment, the ports 147 are between about 150 and 250 mm in diameter which may be just shy of the inlet 110 or outlet 180 diameter to support flow, which may themselves be between about 350 and 400 mm. Similarly, the inlet orifices 145 are also not configured for filtering and may also be larger than the other orifices 130, 155, for example, between about 25 and 75 mm in diameter.

[0030] Referring now to Figs. 3A and 3B, perspective views of the strainer 100 of Fig. 1 are shown accommodated by surrounding support structure 325. Specifically, the structure 325 includes hardware that allows for the presentation of the strainer 100, pump 350 and associated features to be provided in a singular modular assembly 300. Specifically, in Fig. 3 A, the outlet 180 for coupling to the pump 350 is shown along with the inlet 110 and a connector 375 for securing the assembly 300 to a production line 440 as illustrated in Fig. 4. Indeed, modular assemblies 300 may be retrievably installed as part of the overall layout at an oilfield 401 as shown in Fig. 4.

[0031] Recall that the strainer 100 works by filtering while simultaneously allowing for continued production flow. In a certain sense, this may be akin to placing a bucket in the main flow path to collect debris 200 while also perforating the bucket to prevent high velocity hosing out of the debris 200. The assembly may be thought of less as a “strainer” in the conventional sense and more as a bucket that, after some straining through the bottom, may begin to fill up and eventually overflow. That is, over time the filtering of the production fluid flow 185 may eventually lead to a strainer 100 that is full of debris 200 (e.g. within the inner housing 160 as illustrated at Fig. 2C). Thus, while flow may advantageously continue, filtering may eventually cease. In this regard, the assembly 300, including the strainer 100 may be provided in a modular form to facilitate efficient changeout.

[0032] Due to the expense of intervention, retrieving of the modular assembly 300 may not occur until the pump 350 is affected by debris 200. However, due to the unique strainer 100, this is likely pushed forward by a matter of years. For example, the flow assurance provided may help ensure that the pump 350 is largely kept within a “habitable” zone of low pressure loss, reduced risk of hydrates, scale and asphaltene buildup while allowing sand and smaller particulate passage. Once more, when the time comes, a modular changeout allows for enhanced efficiency of the intervention.

[0033] Referring now to Fig. 4, an overview depiction of a subsea oilfield 401 is illustrated which accommodates modular assemblies 300 such as that of Fig. 3B. In this particular layout, multiple well clusters 425, 435 are coupled to manifolds 450, 455. This oilfield 401 includes a conventional offshore platform 460 from which subsea operations may be directed. In this particular example, a production line 440 and bundled electrical/hydraulic lines 410 may run along the seabed between the platform 460 and the cluster locations. Further, at various locations, the modular assemblies 300 may be coupled to the production line 440 to help maintain production flow. Once more, due to the unique capabilities of the strainer of the assemblies 300 as detailed above, the life thereof may be extended without any undue stress on pump flow facilitating capabilities (see arrow 400).

[0034] Referring now to Fig. 5, a partially sectional and cross-sectional schematic representation of an alternate embodiment of the strainer 500 is shown which accommodates a pump 501. When the pump 501 and strainer 500 are incorporated together in this manner, the assembly may be referred to as a pump integrated mixer (PIM) configuration. Thin plate construction may be utilized to provide an overall compact and lightweight assembly for cost savings. While the embodiment looks quite different architecturally, the concept of filtering while allowing for continued circulation of the fluid flow 185 remains.

[0035] The strainer 500 again includes an inlet 511 into which production fluid 185 flows as encouraged by the action of the pump 501. As the fluid flow 185 is drawn in, it encounters a different form of perforation mechanism 550 utilizing different orifice sizing 525, 560 at and above a base 510. Specifically, the fluid flow 185 is again directed from the inlet 511 toward a base 510. Due to the architecture of the flow path, a deflector 580 is utilized to encourage flow toward the base 510 and discourage premature uptake at upper sidewall windows 560. The base orifices 155 of the embodiment of Fig. 1 are replaced with lower sidewall orifices 525 of similar sizing. Thus, debris 200 as shown in Figs. 2B and 2C may begin to accumulate at the base 510. Nevertheless, flow 185 may be permitted to continue through higher elevated orifices 525 and eventually the much larger windows 560 (similar to the ports 147 of Fig. 2C). In one embodiment, the sidewall orifices 525 again are provided with a gradient of sizing (e g. 2-30 mm in diameter) ranging from smaller nearer the base 510 to larger nearer the windows 560.

[0036] Continuing with reference to Fig. 5, the filtered production fluid flow 185 may continue to the interior of the assembly where impellers 580 direct the flow 185 up and eventually out of the strainer 500 through the outlet 585. Clearance between impeller blades may be quite minimal. Thus, as with the embodiment of Fig. 1, the orifice sizing may be tailored with this in mind. Regardless, as with the embodiment of Fig. 1, the strainer 500 may filter while allowing for continued fluid flow 185 but at some point become full. Thus, the strainer 500 may again be provided in a operator-friendly modular form to minimize cost of changeout and installation.

[0037] Referring now to Fig. 6, a flow-chart is shown summarizing a unique embodiment of employing a strainer with a pump at an oilfield that facilitates production fluid flow. Specifically, the production fluid flow may be pumped as indicated at 610. However, as a safeguard to the pump, the fluid may be filtered through a modular strainer (see 630). At the same time, as indicated at 650, fluid flow may be maintained even with debris being fdtered by the strainer. Indeed, as noted at 670, the initial debris that is filtered may be followed by the filtering of additional debris while still maintaining the fluid flow. Nevertheless, the strainer may eventually become full. Thus, it is provided in a modular form for ease of replacement (see 690).

[0038] Embodiments described hereinabove include a system and techniques that uniquely avoid or substantially delay catastrophic pump issues that may be presented by use of a conventional strainer. These embodiments uniquely allow for continued flowing of production fluid even while straining debris from the fluid. That is, the simple act of filtering debris by the strainer does not directly translate into substantial reduction in flow of the production fluid. As a result, efficient production flow may not be impaired. Once more, the strainer itself is not particularly prone to deteriorate itself by the mere act of filtering out debris. Thus, damage to the associated pump by a deteriorating strainer may also be avoided.

[0039] The preceding description has been presented with reference to presently preferred embodiments. However, other embodiments and/or features of the embodiments disclosed but not detailed hereinabove may be employed. Furthermore, persons skilled in the art and technology to which these embodiments pertain will appreciate that still other alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle and scope of these embodiments. For example, the strainer base may be of a conical shape, multiple or differently oriented swirl breakers may be utilized or a host of other architectural modifications undertaken. Along these lines, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.